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Biomedical subjects

W A Myers

Publications and source records attributed to W A Myers.

At least 19 recordsLinked to original sources
PubMed2000

Role of NMDA receptors in adult primate cortical somatosensory plasticity.

We have previously shown that most of the reorganization that typically follows median nerve transection in adult squirrel monkeys is dependent on normally functioning N-methyl-D-aspartate (NMDA) receptors. Here, we have evaluated two additional hypotheses: (1) is the immediate "unmasking" found after median nerve transection NMDA receptor-dependent? and (2) are NMDA receptors necessary for both the initiation and maintenance of the second phase of reorganizational changes, or only the former? To address these issues, we implanted osmotic minipumps subcutaneously to deliver an NMDA receptor antagonist (3-((+/-)-2- carboxypiperazin-4-yl)propyl-1-phosphonic acid, CPP) systemically either before examining the immediate effects of median nerve transection, or after reorganization had presumably occurred. For the first set of experiments, NMDA receptor blockade was initiated either 1 or 4 weeks prior to multi-unit mapping in area 3b followed by transection of the median nerve and remapping of the cortex. In the second set of experiments, median nerve transection was followed 4 weeks later by either 1 or 4 weeks of NMDA receptor blockade prior to terminal mapping. We report that the immediate unmasking of new receptive fields after acute nerve injury is not prevented by NMDA receptor blockade; nor are completely reorganized cortical maps dependent upon NMDA receptors for their maintenance. We conclude that the immediate changes in cortical topography are not due to an NMDA receptor-dependent mechanism, but more likely due to release from tonic inhibition. Furthermore, the later phase of reorganization, as for some forms of hippocampal long-term potentiation (LTP), is dependent on normally functioning NMDA receptors for its initiation, but not for its maintenance.

Animals↗
PubMed2000

Does patient-centered care pay off?

BACKGROUND: Hospitals have adopted patient-centered practices that focus on patients' needs, values, and preferences in hopes of improving quality and controlling costs. Patient-centered practices are intended to involve patients in treatment decisions, increase communication between patients and care-givers, and increase interaction with family members and friends. Rapid adoption of these practices has occurred, even though little is known about the effects of patient-centered care on outcomes and cost. METHODS: A simultaneous equations regression model was developed to examine the reciprocal relationships between patient-centeredness, outcomes, and cost. A consortium of employers obtained data from 52 hospital units in southeastern Michigan. Two hundred randomly selected patients were sampled from all discharges on the medical, surgical, and obstetric units at each hospital for the first three months of 1997; the patients were sent the survey in May. Patient-centeredness was measured by patient reports of whether key clinical events occurred (The Picker Inpatient Survey). Outcomes were assessed by rates of unexpected mortality and complications. Cost was defined by self-insured purchaser payments. RESULTS: Hospital units that were more patient centered were associated with statistically significantly better outcomes and higher costs than those that were less patient centered. The joint relations between outcomes and cost were insignificant. CONCLUSIONS: Patient-centeredness was associated with better outcomes and higher cost. For either the short run or long run, managers, patients, and purchasers should determine whether the improvement in outcomes and patient satisfaction associated with becoming patient centered is worth the investment in costs.

Cost-Benefit Analysis↗
PubMed1998

Somatotopic consolidation: a third phase of reorganization after peripheral nerve injury in adult squirrel monkeys.

It has previously been demonstrated that the central somatosensory topographic reorganization within deprived cortex that follows peripheral nerve injury in adult monkeys occurs in at least two stages: an immediate unmasking period; and a more prolonged period where deprived areas of cortex come to express new receptive fields in a topographically arranged manner. In the present experiments, we have compared cortical topography many months after combined median and ulnar nerve transection with "complete" reorganization evident at relatively short (i.e., 2-5 months) survival times. We find further reorganizational changes in cortical topography with longer survival times. That is, the roughly somatotopic, generally multiple-digit receptive fields frequently observed at the shorter survival times are generally sharpened to more distinct, single-digit receptive fields at longer survival times. We hypothesize that the early crudely topographic maps reflect all available inputs while the refined map is the outcome of an extraction process where only the most useful subset of available inputs is expressed. It is further suggested that this distillation process is a use-dependent phenomenon.

Animals↗
PubMed1997

Denervation-induced sprouting of intact peripheral afferents into the cuneate nucleus of adult rats.

In adult monkeys with dorsal rhizotomies extending from the second cervical (C2) to the fifth thoracic (T5) vertebrae, cortex deprived of its normal inputs regained responsiveness to inputs conveyed by intact peripheral afferents from the face [T.P. Pons, P.E. Garraghty, A.K. Ommaya, J.H. Kaas, E. Taub, M. Mishkin, Massive reorganization of the primary somatosensory cortex after peripheral sensory deafferentation, Science 252 (1991) 1857-1860]. It has been suggested that the extent of this massive topographic reorganization may be due to the establishment of novel connections between intact afferents and neurons denervated after dorsal rhizotomy [P.E. Garraghty, D.P. Hanes, S.L. Florence, J.H. Kaas, Pattern of peripheral deafferentation predicts reorganizational limits in adult primate somatosensory cortex, Somatosens. Motor Res. 11 (1994) 109-117]. Using adult rats with comparably extensive dorsal rhizotomies, we employed anatomical tracing techniques to address this possibility. Subcutaneous hindpaw injections of horseradish peroxidase conjugated to either wheat germ agglutinin or cholera toxin subunit B revealed aberrant expansions of gracile projections into the cuneate and, in one case, external cuneate nucleus within three months of the deafferentation. It seems plausible that such modest sprouting of ascending projections at the level of the brainstem may form functional connections which, through divergence, ultimately drive a larger population of neurons in cortex. This new growth may well account for both the substantial cortical reorganization observed in the 'Silver Spring monkeys' [T.P. Pons, P.E. Garraghty, A.K. Ommaya, J.H. Kaas, E. Taub, M. Mishkin, Massive reorganization of the primary somatosensory cortex after peripheral sensory deafferentation, Science 252 (1991) 1857-1860] and the 'referred sensation' phenomena (see J.P. Donoghue, Plasticity of adult sensorimotor representations, Curr. Opin. Neurobiol., 5 (1995) 749-754 for review) reported to follow proximal limb amputations in humans.

Afferent Pathways↗
PubMed1997

Medicine at the millennium.

What will the future bring? Will biomedical advances move rapidly and affordably into clinical practice, stimulated by the demands of the educated consumer? Or will changes in the way health care is financed and physician inability to stay abreast of clinical changes widen the gap between high-quality and mediocre medical care? Is there a limit to what we can afford to provide, regardless of availability?

Education, Medical↗
PubMed1995

Addictive sexual behavior.

A rationale for the conceptualization of repetitive sexual behaviors as an addiction is presented. Five cases treated by individual psychotherapy are described and certain problems inherent in such treatments are delineated. Other treatment approaches, such as those involving the use of medication, twelve-step groups and cognitive-behavioral techniques are also detailed.

Adult↗
PubMed1994

Addictive sexual behavior.

Case material is presented from two patients suffering from addictive sexual behavior. The term addiction is used because of the intense, driven quality of the behavior and because of its mood-elevating effects. Psychodynamically, the patients' sexual acts helped to undo feelings of rejection at the hands of their mothers and to enhance feelings of lovability and of self-esteem. The behavior also helped to neutralize powerful feelings of rage toward the mother. In one patient, the acts also helped to ease inner turmoil related to an underlying attention deficit disorder. I speculate that some adults with addictive sexual behavior may have underlying attention deficit disorders. In both my patients, the sexual behaviors served the self-regulatory function of alleviating inner feelings of anhedonia and depression. When they decreased their sexual activities during the course of the treatment, they required adjunctive antidepressant medication. The underlying meaning of the medication and countertransference attitudes toward such patients are explored.

Adult↗
PubMed1992

Associations between sexual experiences and fantasies in a nonpatient population: a preliminary study.

We have been interested in devising some methodology short of psychoanalytic therapy to study the relationship of conscious fantasy to personality trends and behavior. Presented here is a pilot study, utilizing the questionnaire technique, the sample consisting of 193 students enrolled at one prestigious urban university, that reports on the prevalence and content of conscious sexual fantasies in a normal (nonpatient) population and their relationship to sexual behaviors. Factor analysis suggested four experience and four fantasy clusters. Those individuals who score high on one experience factor are apt to score high on all other experience factors as well. The same is true of the fantasy factors. Our findings indicate that low sexual activity and low levels of sexual fantasy go together, whereas more sexual experience is connected to a greater range of sexual fantasy. Consequently, erotic fantasies cannot be viewed as compensation for lack of sexual outlet. Instead, there is a positive correlation between the two domains of sexual fantasies and sexual behaviors. Our overall results lead us to conclude that by and large, people are sexual generalists not specialists.

Adult↗
PubMed1989

Gender differences in sexual behaviors and fantasies in a college population.

This study presents male and female responses of 193 university students to questions about sexual experiences and fantasies. There are few significant gender differences in experiences, but many in fantasies. Males fantasized about sex more and exhibited greater interest in partner variation and in the spectrum from domination to sadism. While male sexuality is often described as aggressive/sadistic and female sexuality as passive/masochistic, most men and women in our population do not report fantasies supporting such stereotypes.

Adult↗